The refrigerants referenced herein will soon be illegal in Europe because they contain R-22. However, they will be legal in the rest of the world until 2020. In addition, European law requires disclosure of refrigerant composition. Previously composition was kept as a trade secret for manufacturers blends containing R-22. However, if the focus is on identifying R-125 and R-218 as replacements for R-22, this invention will be applicable for the foreseeable future.
It is an object of the invention to develop a refrigerant blend, which is free of R-22 and which can be used to provide the same refrigeration performance as the previous blend without requiring changes in the compressor, compressor oil, refrigerant liquid-vapor phase separators, or to the heat exchanger arrangement.
Elimination of R-22 was required by German law. However, there is not a pure R-22 substitute, which would provide identical refrigeration performance, a low freezing point temperature, and good miscibility with mineral oil and alkylbenzene oil. Achieving the same performance without R-22 typically requires changes in compressor oil and changes to system components such as expansion devices.
A new charge has been developed that does not require different oil, a different compressor, or changes to the expansion devices, heat exchangers or phase separator. The arrangement was not obvious and required significant development and experimental efforts. Two strategies were considered to substitute R-22. The first one was based on the use of R-125 combined with R-123 and R-124. The second strategy was based on R-218 combined with R-123 and R-124. The pure refrigerant R-125 has a higher freezing point temperature compared to R-218. But R-125 is more soluble with other components like R-23, R-124 and R-123. This characteristic helps to reduce freezing temperatures of the blend at low temperature in the system.
For both strategies a proper proportion between R-124 and R-123 is important. This proportion is a tradeoff between a higher refrigeration capacity for R-123, a lower freezing temperature for R-124, and better oil management provided by R-124 downstream of the first phase separator by virtue of R-124""s higher vapor pressure.
Development was completed of new systems with the above refrigerants. The new charges maintain similar operating compressor temperatures and pressures. Temperatures provided are within 4 C of the old rated performance for all models. Representative data of the systems with the R-22 containing mixture and the R-22 free mixture are shown in Table II. The blend development was done on auto-refrigerating cascade systems (Missimer U.S. Pat. No. 3,768,273). This cycle is a modified configuration of the Klimenko cycle (A. P. Klimenko xe2x80x9cOne-flow cascade cyclexe2x80x9d, IIR Int""l Congress of Refrig./Copenhagen, Denmark, 1959). However, testing was done on a single expansion device system similar to a U.S. Pat. No. 5,44,658 type system. Therefore, the novel blends could be employed in a U.S. Pat. No. 5,441,658 system. It is anticipated that these mixtures are applicable to any configuration of the Klimenko cycle as well.
Refrigerant blends having the following compositions are for use in a closed loop vapor compression refrigeration cycle. The cycle is selected to achieve refrigeration in the temperature range of xe2x88x9270 C to xe2x88x92165 C, based on a single-stage compressor. The blends replace R-22 by using R-125, or R-125 with R-124, or R-218, or R-218 with R-124. Relative to the R-22 blend, the flammability of the replacement blend is the same or less. These replacement blends were developed for use with compressor oils traditionally used with R-22 such as mineral oil or alkyl benzene oil.
The individual developed blends in accordance with the invention are shown in Table I (FIG. 1) and indicated as Blend A, Blend B, etc. Also shown in the table are the model numbers of developed commercial products (IGC Polycold Systems, Inc., San Rafael, Calif.), which use these blends.
For example, a prior art refrigeration unit, used a mixture, containing R-123, R-22, R-23, R-170, R-14, and argon. This mixture has been successfully replaced with Blend B (Table I) to achieve the goal of providing equivalent refrigerant performance without using R-22.
Further, in accordance with the invention, another component may be added to the above compositions provided that the ratios of the listed components (Table I) remain in the same proportions relative to each other. Also, it is recognized that R-218 and R-125, which have been used exclusively, can also be combined in the same blend.
Weng, in U.S. Pat. No. 5,408,848, describes a CFC free blend which uses HCFC""s. The Weng inventors note the difficulty in maintaining acceptable discharge temperatures when using their blend. Hardware modifications were required to make their blend work in prior equipment. The present invention enables the same performance to be provided without making hardware modifications as described by the Weng Patent.
Accordingly, an object of the invention was development of improved refrigerant blends which are free of R-22 and which can be used to provide the same refrigeration performance as a previous blend with R-22 without requiring changes in the compressor, compressor oil, refrigerant liquid-vapor phase separators, and heat exchanger arrangement.
The invention accordingly comprises blends of refrigerants possessing the characteristics, properties and the relation of components which are exemplified in the blends herein-after described, and the scope of the invention will be indicated in the claims.